Foldable sofa sleepers having pivotally interconnected head, body, intermediate and foot sections movable between a fully folded or retracted position within the sofa frame for use as a seat, and an extended, unfolded position for use as a bed, are known in the art. Prior foldable sofa sleepers are typically characterized by a relatively poor sleeping surface and a less than desirable seating surface. Most prior sofa sleepers represent a compromise between a good bed and a good sofa in that no matter how well constructed, they are not as good for sleeping as most beds and not as good for seating as most sofas. Poor sleeping quality can be attributed to the provision of a poor foundation beneath the mattress, and poor seating quality stems from the same problem, a lack of firm foundation beneath the seat cushions.
Most sofa sleepers employ a wire fabric material or a sheet of woven polypropylene or other plastic materials extending between the side rails of the head, body, intermediate and foot sections of the sofa bed fixture for support of a foldable mattress. Wire fabric alone or plastic sheeting alone has proven to be unsatisfactory in providing sufficient support for both the mattress and seat cushions of the sofa sleeper. The mattress support sags excessively when the frame is unfolded for use as a bed and when providing a seat in the folded position.
In an effort to provide a better foundation beneath the mattress and seat cushions, attempts have been made to reinforce the wire fabric or plastic sheeting in all of the frame sections and particularly the body frame section of the sofa bed fixture where most of the weight is applied in using the sofa sleeper either as a bed or seat. Supports have been positioned beneath the fabric or plastic sheeting material in the area of the body frame section to help prevent sagging. While known supports for the fabric or plastic sheeting have provided improved foundation support for the mattress and seat cushions, such supports have failed to provide the user with the desired feel of a mattress supported by box springs when the sofa sleeper is used as a bed.